Composition board



United States Patent Ofifice 3,026,242 Patented Mar. 20, 1952 3,026,242 CGMPGSITEGN BGARD John Robert Emery and Robert Morrow, In, Wilmington,

DeL, assignors to E. I. du Pont de Nemours and Comgreat increase in cost. But even more important is that such materials should achieve the desired higher stitch tensile strength without the loss of other needed properties such as flexibility and resistance to delamination, and

Pam, Wnminpmn 13% a wmmafien of Dakaware 5 without necessitating laminating fabrics to the board.

Nomi-win Filed Aii 6, reel, Ser- No. 676,481 an b1ect 9 thls to PTOYIde new i 4 Claims (Cl. 162 146) position board suitable for use in shoe innerscles which has a high stitch tensile strength combined with the flex1- This invention relates to new products and more bility and resistance to delamiuation. It is another ob specifically to new composition boards reinforced with 10 ject of this invention to provide composition boards of synthetic polymer filaments. high tensile strength and resistance to flex failure and Composition boards conventionally contain cellulosic impact failure. Another object of this invention is to pulps which are beaten up with water and are formed provide composition boards containing synthetic organic into sheets or boards on cylinders or Fourdrinier mapolymer filaments which contribute to greater tensile chines. Such boards are frequently reinforced with resin r g and resistance to tearing and impact failurebinders which improve the stability, water resistance, and These objects are achieved in a composition board resistance to delarnination of the products. While many h as a shoe i r based on kraft p p n nvarieties of pulp are used for different kinds of boards, taming between 3 and 10% y Weight (based on total1 it is customary, when high strength articles are desired, Weight of P p P1115 filaments) of high tenacity Synthetic to use kraft pulp in place of cheaper but lower strengt Organic P y filaments in the form of Staple fibers at materials, least /2 an inch long and not over 1 inch long and at Among the uses of composition boards which require ieast 1O denier P filament and Preferably about 15 high strength material are shoe innersoles. In the condenier per filament, the composition board being bonded struction f t h 'th upper i tit h d t th with a flexible elastomeric resin binder present to the innersole and then the innersole is in turn stitched to the eXteht of at least d not ver 25% of the total outersole. This construction puts a good deal of strain Weight 05 the Composition hOaIdon the innersole material since the two rows of stitches position boards of the type specified can be preare close to one anoth d ar di t d i it pared on conventional cylinder or Fourdrinier machines ways. There is a severe tearing force which is constantly With no Change in Processing; in fact, because of the exerted against the innersole material by these two rows Presence of the Coarse Synthetic fiber filaments, the of stitches and the stress is particularly great when the board is easier to Process than conventional ds shoe is flexed as happens continually in normal walking. Cause the at r drains out more freely and rapidly and There is little or no abrasion stress exerted against inner- Cuts down the Cycle time fohmahufaethfe The soles, and th compressive fo are moderate, b h positions within this invention are superior to conventensile stresses and stitch tensile stresses on shoe innertiohal Composition beards made Without the Synthetic soles are extremely high and, when failure does occur, Organic fiber because y have a much higher Stitch tellit is usually at the points of stitching. For this reason, Sne strength and resistance to tearing Without y Sacrimaterials of high stitch tensile strength are desired for fice of other desirable Physical Properties, d these f use as shoe innersole. The most satisfactory such ma- Vantagas can be achleved at only a modest increase 111 terial is leather, but leather cannot be employed in high cost volume (low cost) shoe manufacturing operations be- ExamPles 9 the pracuce of Present invention are cause of the expense. For this reason, most shoe manu- Summanzed m Table I following- I these examples, facturers employ kraft-pulp-based composition boards for boar-d5 are cOn-structsd on a cyl-md-er maqhme usmg as h 1 H h th t a 1 ft 'fHIIllSh the mixture of fibers indicated in each case. s 06 innerso oweverieven W en The boards are tested for stitch tensile strength and eX- pulp is used, the rate of failure of composition innersoles amined for delaminafion by manual testing A Varisty of has been llhdeslfahly gh Partleulafly 111 Shoes Where formulations are illustrated and, as the table shows, comthe lhhel'soles must he of hght Weight for p in positions of the present invention offer a unique com- Womens and childrens shoes. Accordingly, woven fabbination of advantages.

Table I Synthetic 21 332 3? fiberDPF/ Binder; Ex, Composition length, percent Processing characteristics inches Stitch Delaminatensile, tion 1b./pt. tendency I Kraft, chrome leather scrap (control), 50% 15 Standard .35 Low. II Kraft, 50%; chrome leather scrap (control), 50% .l 20 .d0 .35 Low. III Kraft, 47%; chrome leather scrap, 50%; poly(heran1ethyl- 15% 20 Very high improved wet strength, .70 Low.

eue adiparnide) fiber, 3%. faster drainage on cylinder. IV Kraft, 45%; chrome leather scrap, 50%; poly(hexamethyl- 15 4 20 See Ex. III 75 Low.

cne adipamide) fiber, 5%. V Kraft, 45%; chrome leather scrap, 50%; poly(ethylene 12% Low tercphthalate) polyester fiber, 5%.

1 Pliolite 2001 latex resin (a flexible butadiene rubber based adhesive) manufactured by Goodyear Tire and Rubber Company.

rics are laminated to the thinner innersoles to improve stitch tensile strength.

It would be desirable to prepare a composition board of increased stitch tensile strength which could withstand successfully the great strains to which shoe innersoles are subjected. It would be, of course, most desirable that such a composition could be made without Other synthetic fibers which are useful in this invention include high tenacity acrylic fibers such as polyacrylonitrile and copolymers containing at least about bound acrylonitrile, high tenacity rayon, etc. In all cases, the stated high denier per filament fibers of the stated length are necessary.

While the examples show the preparation of composition boards using a specific latex resin, other flexible resins, based on latex, synthetic rubber formulations, neoprene and other elastomers are also satisfactory, provided that they bond the fibers of the composition as firmly as the resin exemplified. 7

As the examples show, the practice of the present invention gives a product with markedly improved physical properties at only a modest increase in cost. The practice of the present invention, however, is highly specific. It is not sufficient merely to add synthetic fiber filaments. The filaments must be present in a certain concentration range, and the filaments must be of a certain physical size. In addition, it is necessary that the resin content of the board be increased to offset the lower bonding tendency of the synthetic filaments of this invention. However, when all of these requirements are met, there is obtained a product which has superior physical properties and is highly useful as an article in manufacture.

While the examples of this invention have described the preparation of composition boards suitable for shoe innersoles, it is quite possible and practical to employ the same principles in the manufacture of other types of composition board. For example, tempered hardboard prepared from wood waste and bonded under high pressure and temperature with the lignins present in the bark of the wood waste is a Well-known article of commerce. This composition board ofiers many attractive advantages for home construction, as a wall and ceiling surface, as a liner for closets and drawers and many other uses. The product is smooth, abrasion resistant and durable. However, it sufiers from a lack of resistance to sudden impact. This undesired weakness can be overcome by the incorporation of 3 to of heavy denier per filament synthetic organic fiber filaments as shown in Table I. When 3 to 5% of such filaments are added, the impact resistance of the board is greatly increased and other properties do not suffer. If too large a percentage of synthetic filament is added, the board does not bind satisfactorily. If low denier per filament or short staple fibers are used, the inclusion of the organic filament does not contribute satisfactorily to the impact strength of the board. Similarly, the principle of the present invention can be applied in the manufacture of other types of composition board wherever a slight increase in cost can be tolerated for the achieving of substantially greater strength and its attendent advantages.

The claimed invention:

1. A composition board suitable for a shoe innersole comprising kraft pulp containing in admixture therewith, high tenacity synthetic organic polymeric fibers in the amount of from about 3% to about 10% based upon the weight of kraft pulp plus polymeric fibers, and having an average length between about /2 and about 1 inch and a denier per fiber of between about 10 and about 15, said composition board being bonded with a flexible elastomeric resin binder present in an amount between about 18% and about 25%, based upon the total weight of the composition board.

2. The composition board of claim 1 in which the fibers are polyethylene terephthalate.

3. The composition board of claim 1 in which the fibers are nylon.

4. The composition board of claim 3 in which the nylon is polyhexamethylene adipamide.

References Cited in the file of this patent UNITED STATES PATENTS 2,526,125 Francis Oct. 17, 1950 2,653,870 Kast Sept. 29, 1953 2,719,802 Nottebohm Oct. 4, 1955 2,723,935 Rodman Nov.'15, 1955 2,777,787 Bragg Jan. 15, 1957 FOREIGN PATENTS 674,577 Great Britain June 25, 1952 687,041 Great Britain Feb. 4, 1953 708,622 Great Britain May 5, 1954 

1. A COMPOSITION BOARD SUITABLE FOR A SHOE INNERSOLE COMPRISING KRAFT PULP CONTAINING IN ADMIXTURE THEREWITH HIGH TENACITY SYNTHETIC ORGANIC POLYMERIC FIBERS IN THE AMOUNT OF FROM ABOUT 3% TO ABOUT 10% BASED UPON THE WEIGHT OF KRAFT PULP PLUS POLYMERIC FIBERS, AND HAVING AN AVERAGE LENGTH BETWEEN ABOUT 1/2 AND ABOUT 1 INCH AND A DENIER PER FIBER OF BETWEEN ABOUT 10 AND ABOUT 15, SAID COMPOSITION BOARD BEING BONDED WITH A FLEXIBLE ELASTOMERIC RESIN BINDER PRESENT IN A AMOUNT BETWEEN ABOUT 18% AND ABOUT 25%, BASED UPON THE TOTAL WEIGHT OF THE COMPOSITION BOARD. 